JP3374726B2 - How to photograph the mixture distribution - Google Patents

Description

Description: BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to a method for photographing a fuel distribution state in a fuel mixture used for an engine or the like. 2. Description of the Related Art For example, an engine is operated by injecting a mixture of fuel and air into a cylinder and compressing and exploding the mixture. In order to improve the characteristics of such an engine, it is effective to understand the fuel distribution state in the air-fuel mixture during the compression process and the like and its behavior. Conventionally, as a method of grasping the distribution of fuel in an air-fuel mixture, there has been proposed a method of visualizing the fuel distribution using a fluorescent agent which is excited by a laser and fluoresces. For example, in J.I. Rebox, et al. , SAE
Paper No. 941988 (1994) (conventional example 1). That is, a measurement fuel obtained by adding only toluene (boiling point: 111 ° C.) as a fluorescent agent to isooctane (boiling point: 99 ° C.) as a single base fuel is used to form a mixture of the fuel and air. Then, the mixture is irradiated with a laser, and the fluorescence from the toluene (fluorescent agent) generated at this time is photographed to visualize and measure the fuel distribution in the spark ignition engine. [0004] J. J. C. Spindal, et a
l. , SAE Paper No. 950106 (19
95) (conventional example 2). That is, a measurement fuel obtained by adding only one kind of fluorescent agent having a different boiling point to isooctane (boiling point: 99 ° C.) as a single base fuel is used to form a mixture of this fuel and air. Then, the mixture is irradiated with a laser, and the fluorescence from the fluorescent agent generated at this time is photographed to visualize and measure the fuel distribution in the engine. [0005] As one kind of fluorescent agent to be added,
Butyraldehyde, a fluorescent agent for low boiling point
(Boiling point 75 ° C), Valera which is a fluorescent agent for medium boiling point
By using Ldehyde (boiling point 103 ° C.) and Heptaldehyde (boiling point 153 ° C.), which are fluorescent agents for high boiling point, respectively, the low, medium and high boiling point fuel distribution in the spark ignition engine at the time of cold start can be individually determined. Measuring. [0006] However, the conventional method for visualizing an air-fuel mixture has the following problems. That is,
In the above conventional example 1, a fuel obtained by adding toluene to a single base fuel made of isooctane is used as a fuel for measurement. The fuel for this measurement has a large difference in distillation characteristics as compared with gasoline or the like which is actually used for the engine. [0007] For example, gasoline usually contains many boiling components ranging from 30 to 200 ° C, and the distillation characteristics of the fuel measured in Conventional Example 1 in which only a fluorescent agent (toluene) having a boiling point of 111 ° C is added to isooctane having a boiling point of 99 ° C. to differ greatly. Therefore, in Conventional Example 1, the distribution of the fuel for measurement is
There is a problem that the distribution state of the fuel (gasoline or the like) used in an engine or the like is different. Specifically, for example, during cold start of a gasoline engine, the degree of adhesion of low-boiling components and high-boiling components in fuel to intake ports and the like is different, and the distribution state of each component is different. . However, it is impossible to faithfully reproduce such a characteristic distribution in the measurement fuel obtained by mixing the single base fuel and the fluorescent agent. The reason that gasoline or the like is not directly used as the fuel for measurement is that gasoline and the like often contain many components that emit various fluorescent light, so that accurate visualization cannot be performed by the laser irradiation. . Also, in the above-mentioned conventional example 2, as the fuel for measurement, a fuel mainly composed of a single base material made of isooctane and added with one kind of fluorescent agent is used.
For this reason, similarly to the conventional example 1, the measurement fuel has a problem that the distillation characteristics are significantly different from those of gasoline or the like, and the distribution state of gasoline or the like cannot be faithfully reproduced. Further, in the conventional example 2, the type of the fluorescent agent to be added is changed, that is, the boiling point of the fluorescent agent is changed so that the fuel distribution of the low, middle and high boiling points in the spark ignition engine at the time of the cold start is changed. Measured individually. In this case, since the obtained low, medium, and high boiling point fuel distributions are at different timings (cycles), it is difficult to evaluate each distribution state in the same cycle in association with each other. SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and is capable of faithfully reproducing the distribution state of a fuel in practical use, and furthermore, the distribution of a plurality of components having different boiling points in the fuel at the same timing. It is an object of the present invention to provide a method for photographing an air-fuel mixture distribution in which a state can be simultaneously obtained as a photographed image. SUMMARY OF THE INVENTION The present invention is a method for photographing a distribution state of a fuel contained in an air-fuel mixture disposed in a measurement area, comprising: a plurality of base fuels having weak fluorescence characteristics; And at least two types of fluorescent agents having different fluorescence wavelength ranges from each other to produce a fuel having predetermined distillation characteristics, and then mixing the fuel with air to produce an air-fuel mixture. By irradiating a laser for fluorescence excitation to the above-mentioned air-fuel mixture disposed in the measurement area, and simultaneously capturing the fluorescence generated from each fluorescent agent separately in accordance with each fluorescent wavelength range, it is possible to perform imaging for each type of the fluorescent agent. There is provided a method for photographing an air-fuel mixture characterized by obtaining an image. What is most notable in the present invention is that a plurality of base fuels having weak fluorescence characteristics and a plurality of fluorescent agents having different boiling points and fluorescence wavelength ranges are mixed to form a fuel having predetermined distillation characteristics. It is to produce. Then, the fluorescence generated from each fluorescent agent is separately and simultaneously photographed according to each fluorescence wavelength range. The above-mentioned base fuel having a weak fluorescence characteristic means a base fuel which emits no fluorescence or hardly emits fluorescence even when it receives an excitation laser. That is, a liquid mixture of liquids of various boiling points that do not absorb the excitation laser and do not emit fluorescence can be used as the base fuel. Also, a plurality of base fuels are used. This is to obtain a predetermined distillation characteristic described later. Therefore, as the base fuels, those having different boiling points and those having different mixing ratios are used. The above-mentioned fluorescent agent refers to a substance having a property of emitting fluorescence upon receiving an excitation laser. As the above-mentioned fluorescent agent, at least two or more types having different boiling points and fluorescent wavelength ranges are used. As the boiling point, a boiling point equivalent to the boiling point of the fuel component whose distribution state is to be visualized is selected. The fuel is prepared by mixing the plurality of base fuels and the plurality of fluorescent agents to have predetermined distillation characteristics. Here, the predetermined distillation characteristics refer to the same or similar distillation characteristics as those of a practical fuel such as gasoline. Such a predetermined distillation characteristic can be obtained by adjusting the addition amounts of the plurality of base fuels and the fluorescent agent. It should be noted that if the practical fuel has a weak fluorescent property, it can be used as it is as the fuel. As the laser for fluorescence excitation, YAG
Various lasers such as a laser, an excimer laser, and a dye laser can be used. However, the laser wavelength for fluorescence excitation is preferably shorter than the entire fluorescence wavelength range emitted by the fluorescent agent. As a result, it is possible to obtain a photographed image representing an accurate distribution state. Simultaneous photographing of the fluorescence generated from each of the fluorescent agents can be performed, for example, by simultaneously using two or more photographing cameras equipped with optical filters corresponding to the respective fluorescence wavelength ranges. Also, a stereo scove can be used together. Further, as the photographing camera, for example, a still camera, a video camera, a CCD camera, a CCD camera with an image amplifier, or the like can be used. Further, other image detecting devices usually used in this field can be used. Further, other devices usually used in this field may be used in combination. The photographed image can be in various forms such as a photograph and a display on a display. Next, the operation of the present invention will be described. In the present invention, the distillation characteristics of the fuel to be produced are adjusted to predetermined distillation characteristics by using the plurality of base fuels and the plurality of fluorescent agents. Therefore, the fuel used in the present invention is
For example, it can be matched with the distillation characteristics of practically widely used practical fuels such as gasoline. Therefore, the distribution state of the fuel in the air-fuel mixture can reproduce the distribution state of the practical fuel. Further, the above-mentioned fuel contains at least two kinds of fluorescent agents. In addition, the boiling point and the fluorescent wavelength region of each fluorescent agent are different from each other. Therefore, when the air-fuel mixture is disposed in the measurement region, each fluorescent agent can represent a characteristic distribution state of the fuel component equivalent to its boiling point. That is, the concentration of the low-boiling point fluorescent agent is high in the portion where the concentration of the low-boiling point component is high, while the concentration of the high-boiling point fluorescent agent is high in the portion where the concentration of the high-boiling point component is high. Then, each of the fluorescent agents emits fluorescence by irradiating the above-described laser for fluorescence excitation to the air-fuel mixture in the measurement area. The intensity of this fluorescence appears depending on the distribution state of each fluorescent agent. That is, the fluorescence is weak in the portion where the distribution concentration of each fluorescent agent is low, and the fluorescence is strong in the portion where the distribution concentration is high. Also,
At this time, since the base fuel has a weak fluorescent property, it is not affected by these. Next, the fluorescence from each fluorescent agent is photographed simultaneously for each fluorescence wavelength. This makes it possible to obtain captured images corresponding to the fluorescent agents. The obtained captured images are captured simultaneously as described above. Therefore, for example, when there are two types of fluorescent agents, each photographed image shows a typical distribution state of the high boiling point component and the low boiling point component at the same timing. Further, for example, when there are three types of fluorescent agents, representative distribution states of a high boiling component, a medium boiling component, and a low boiling component at the same timing are shown. Therefore, each of the obtained captured images faithfully reproduces the distribution state of a plurality of boiling point components in the fuel at the same timing. When the above photographing is repeated at regular time intervals, a temporal change in the distribution state of each boiling point component can be obtained as a photographed image. Therefore, in this case, for example, the behavior of the air-fuel mixture distribution in the engine can be accurately grasped. Embodiment 1 An air-fuel mixture distribution photographing method according to an embodiment of the present invention will be described with reference to FIGS. 1 and 2. As shown in FIG. 1, the method of photographing the air-fuel mixture distribution of this embodiment is a method of photographing the distribution state of the fuel contained in the air-fuel mixture disposed in the measurement region. Then, a plurality of base fuels having weak fluorescence characteristics and three types of fluorescent agents having different boiling points and fluorescent wavelength ranges are mixed to obtain a predetermined distillation characteristic E10 as shown in FIG.
Is prepared. Next, the fuel and air are mixed to produce an air-fuel mixture. Next, a laser for excitation of fluorescence is applied to the air-fuel mixture disposed in the measurement area, and the fluorescence generated from each of the fluorescent agents is simultaneously photographed separately according to each fluorescent wavelength range. To obtain a photographed image. The above-described fluorescent agent and fuel will be described more specifically with reference to FIGS. FIG. 1 shows the temperature on the horizontal axis and the evaporation rate of the fluorescent agent on the vertical axis. Further, the distillation characteristics of each of the three types of fluorescent agents E11, E12, and E13 and the distillation characteristics of a fuel E10 produced by using these fluorescent agents and a plurality of base fuels are shown together. Further, in FIG. 1, the distillation characteristics of the practical fuel are plotted with a circle. In FIG. 2, the horizontal axis represents the wavelength of the fluorescence, and the vertical axis represents the fluorescence intensity. As is known from FIG. 1 and FIG.
As the types of fluorescent agents E11, E12, and E13, those having different boiling points (FIG. 1) and whose fluorescent wavelength regions hardly overlap (FIG. 2) are used. That is, each fluorescent agent is shown in FIG.
As shown in the figure, a low-boiling fluorescent agent E11 corresponding to a low-temperature region, a medium-boiling fluorescent agent E12 corresponding to a medium-temperature region, and a high-boiling fluorescent agent E13 corresponding to a high-temperature region in the distillation characteristics E10 of the prepared fuel. It can also be seen that the distillation characteristics E10 of the fuel prepared from the above-described fluorescent agent and a plurality of base fuels are the same as the distillation characteristics (（) of the practical fuel. In this embodiment, a fuel-air mixture is prepared by mixing fuel having the above-mentioned distillation characteristics and air. Next, the air-fuel mixture is sent into the container in which the measurement region is set, and a laser for fluorescence excitation is irradiated at a predetermined timing when the fuel distribution is to be measured. As a result, in the air-fuel mixture that has been subjected to the laser irradiation, each of the fluorescent agents emits fluorescence. Then, the fluorescence emitted from the air-fuel mixture is distributed to three spectra. Then, each spectrum is analyzed by the above 3
Each of the fluorescent agents E11, E12, and E13 is passed through a filter that transmits only the fluorescence corresponding to the fluorescence wavelength region, and is photographed by a camera. Thereby, three types of photographed images showing the fuel distribution at the predetermined timing can be obtained. More specifically, a photographed image showing the distribution of low-boiling components in the fuel, which was obtained by photographing the fluorescence emitted by the low-boiling fluorescent agent, and a fluorescent image produced by the medium-boiling fluorescent agent, A photographed image showing the distribution of mid-boiling components in the fuel,
A photographed image showing the distribution of high boiling point components in the fuel, obtained by photographing the fluorescence emitted by the high boiling point fluorescent agent, is obtained. Further, by repeating the laser irradiation and the photographing at different timings, it is possible to know the temporal behavior of the distribution of each component. Embodiment 2 This embodiment is a more specific example of Embodiment 1. That is, in this example, as shown in Table 1, a fuel having the same distillation characteristics as a commercially available so-called regular gasoline was produced using five types of base fuels and two types of fluorescent agents. Table 1 shows the components, boiling points and mixing ratios of each base fuel and fluorescent agent. As known from Table 1,
Acetone serves as a low boiling point fluorescent agent and 1,2,3-trimethylbenzene serves as a high boiling point fluorescent agent. [Table 1] FIG. 3 shows the distillation characteristics E20 (solid line) of the fuel prepared according to the mixing ratios shown in Table 1, the distillation characteristics (○) of the commercial regular gasoline, and the distillation characteristics E2 of the low-boiling fluorescent agent.
1 shows the distillation characteristics E22 of the high boiling point fluorescent agent. Note that FIG.
Is a graph in which the horizontal axis represents temperature (° C.) and the vertical axis represents evaporation (volume%). As can be seen from FIG. 3, it can be seen that the fuel produced according to the present example has a distillation characteristic substantially equal to that of a commercial regular gasoline as a practical fuel. FIG. 4 shows the relationship between the temperature and the evaporation rate of the low-boiling fluorescent agent E21 and the high-boiling fluorescent agent E22. That is,
In the figure, the horizontal axis represents temperature, and the vertical axis represents the evaporation rate (mol / degree). As can be seen from FIG.
Is about 70 ° C, and the high boiling fluorescent agent E22 is about 180 ° C.
, Evaporation is most active. from these things,
It can be said that the low-boiling fluorescent agent and the high-boiling fluorescent agent of this example can be tracers of low-boiling components and high-boiling components in the fuel. FIG. 5 shows the fluorescence spectra of the low-boiling fluorescent agent E21 and the high-boiling fluorescent agent E22. In the figure, the horizontal axis represents wavelength (nm) and the vertical axis represents fluorescence intensity (arbitrary). The wavelength E29 of the fluorescence excitation laser is 248 nm.
As can be seen from the figure, the fluorescent wavelengths of the low-boiling fluorescent agent E21 and the high-boiling fluorescent agent E22 are greatly different, and it can be understood that the optical filters corresponding to the fluorescent wavelength ranges can be separately and simultaneously photographed according to each fluorescent wavelength. . Therefore, in this embodiment, the distribution state of each boiling point component can be taken out independently and simultaneously as a photographed image. FIG. 6 shows a spectrum of a mixture of the base fuels shown in Table 1 alone (not including a fluorescent agent). The horizontal and vertical axes in FIG. 6 are the same as those in FIG. According to FIG. 6, none of the base fuels shown in Table 1 emits fluorescence.
Therefore, it is understood that the photographed image is not adversely affected. Embodiment 3 In this embodiment, a fuel having the same distillation characteristics as a so-called light gasoline was produced, and the distribution of the fuel in the mixture was photographed. Light gasoline has a 90% distillation temperature lower by about 50 ° C. than that of commercial regular gasoline, and is about 130 ° C. to 140 ° C. As shown in Table 2, the fuel of this example was prepared using six types of base fuels and two types of fluorescent agents. For the components, boiling points and mixing ratios of each base fuel and fluorescent agent,
It is shown in Table 2. As can be seen from Table 2, acetone serves as a low-boiling fluorescent agent, and O-xylene serves as a high-boiling fluorescent agent. [Table 2] FIG. 7 shows a distillation characteristic E30 (solid line) of the fuel prepared according to the mixing ratios shown in Table 2. In this case, the horizontal axis represents temperature (° C.), and the vertical axis (left) represents the amount of evaporation (% by volume). Table 3 summarizes the distillation temperatures of the fuel. From FIG. 7 and Table 3, it can be seen that the fuel of this example has almost the same distillation characteristics as light gasoline. [Table 3] FIG. 7 shows the relationship between the temperature and the evaporation rate of the low-boiling fluorescent agent E31 and the high-boiling fluorescent agent E32.
The vertical axis (right) in this case is the evaporation rate (mol / degree). As can be seen from the figure, the low-boiling fluorescent agent E31 is approximately 70 ° C.
At about 130 ° C.
Evaporation is most active. From these facts, it can be said that the low-boiling fluorescent agent E31 can be a tracer for the component having a 10% distillation temperature in the fuel, and the high-boiling fluorescent agent E32 can be a tracer for the 90% distillate component. FIG. 8 shows the fluorescence spectra of the low-boiling fluorescent agent E31 and the high-boiling fluorescent agent E32. The wavelength E29 of the fluorescence excitation laser is 248 nm. As can be seen from the figure, the fluorescent wavelengths of the low-boiling fluorescent agent E31 and the high-boiling fluorescent agent E32 are greatly different, and it can be seen that an optical filter corresponding to the fluorescent wavelength region can be used to simultaneously shoot separately according to each fluorescent wavelength. . Therefore, also in the present embodiment, the distribution state of each boiling point component can be taken out independently and simultaneously as a photographed image. Note that fluorescence from only the base fuel shown in Table 2 was not observed, and did not adversely affect the photographed image. Fourth Embodiment This embodiment is a specific example of a method for photographing an air-fuel mixture distribution in a case where a section perpendicular to an axis in an engine cylinder is used as a measurement region. As shown in FIG. 9, the engine cylinder 51 is provided with quartz glass windows 511 and 512 for transmitting sheet-like excitation light (fluorescence excitation laser) 34 and an emission window 513 for observation light (fluorescence) 35. A transparent window 521 made of quartz glass for transmitting the observation light 35 is provided in the piston 52. Then, the observation light 35 transmitted through the window 521 changes its direction by the mirror 531 and is emitted from the emission window 513. The fuel is the same as that shown in the second embodiment, and acetone is used as a low-boiling fluorescent agent and 1,2,3-trimethylbenzene is used as a high-boiling fluorescent agent. The light source is a KrF excimer laser (wavelength 248)
nm), and a sheet-like excitation light 34 is formed, and the excitation light 34 is made to enter from a window 511 of the engine cylinder 51. The excitation light 34 passes through the engine cylinder 51, and thereby excites the low-boiling fluorescent agent and the high-boiling fluorescent agent in the fuel. The first fluorescent light (wavelength of about 280 to 320 nm) of the low-boiling fluorescent agent and the high-boiling fluorescent light are emitted. Second fluorescence of the agent (wavelength about 340 nm to 500
nm). The observation light 35 including the first fluorescence and the second fluorescence passes through the window 521 of the piston 51 and passes through the mirror 5.
The direction is changed at 31 and the light is emitted from the emission window 513. The observation light 35 is split into two by the split mirror 12, passes through the first filter 211 and the second filter 212, and captures the first image and the second image by the first camera 221 and the second camera 222, respectively. Is done. The first image shows the distribution of high boiling components in the fuel, and the second image shows the distribution of low boiling components. As described above, in the present embodiment, components having different boiling points in the fuel can be photographed at the same time. Then, in order to measure the instantaneous fuel distribution at a desired timing of the engine, the excitation light 34 is oscillated in a pulse shape (in this example, the light emission time is about 20 n).
s). Then, the shutters of the cameras 221 and 222 are operated at high speed in synchronization with the oscillation of the excitation light 34 (in this example, 100 ns or less). As a result, the distribution behavior of components having different boiling points in the fuel at a desired timing of the engine can be simultaneously photographed. Fifth Embodiment As shown in FIG. 10, this embodiment is different from the fourth embodiment in that
9 is another embodiment in which a stereoscope 24 is used to measure the first image and the second image with one camera 23. That is, the observation light 35 is transmitted to the first filter 211 and the second filter 212 of the stereoscope 24.
To the lens 245 from the mirrors 241-244.
Are taken by a single camera 23. The first image passed through the first filter 211 is detected in a half area of the detection surface of the camera 23, and the second image passed through the second filter 212 is detected by the camera 2.
No. 3 is detected in the remaining 1/2 area of the detection surface. Others are the same as in the fourth embodiment. As described above, according to the present invention, it is possible to faithfully reproduce the distribution state of the fuel in practical use, and to determine the distribution state of a plurality of components having different boiling points in the fuel at the same timing. It is possible to provide a method of photographing the mixture distribution, which can be simultaneously obtained as a photographed image individually.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory diagram showing distillation characteristics of each fluorescent agent and fuel in Embodiment 1. FIG. 2 is an explanatory diagram showing a fluorescence wavelength region of each fluorescent agent in the first embodiment. FIG. 3 is an explanatory diagram showing distillation characteristics of each fluorescent agent and fuel in Embodiment 2. FIG. 4 is an explanatory diagram showing an evaporation characteristic of each fluorescent agent in a second embodiment. FIG. 5 is an explanatory diagram showing a fluorescence spectrum of each fluorescent agent in a second embodiment. FIG. 6 is an explanatory diagram showing a fluorescence spectrum of a base fuel in Embodiment 2; FIG. 7 is an explanatory diagram showing a distillation characteristic of a fuel and an evaporation rate of each fluorescent agent in a third embodiment. FIG. 8 is an explanatory diagram showing a fluorescence spectrum of each fluorescent agent in the third embodiment. FIG. 9 is an explanatory diagram showing a configuration of an imaging device for air-fuel mixture distribution according to a fourth embodiment. FIG. 10 is an explanatory diagram showing a configuration of an imaging device for air-fuel mixture distribution according to a fourth embodiment. [Explanation of Codes] . . 11. An imaging device for air-fuel mixture distribution; . . Split mirror, 211. . . First filter, 212. . . Second filter, 221, 222. . . Camera, 34. . . Excitation light (laser for fluorescence excitation), 35. . . Observation light (fluorescence), 51. . . Engine cylinder, 52. . . piston,

────────────────────────────────────────────────── (5) References JP-A-5-149877 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01N 33/22 G01N 21/64 JICST file ( JOIS)

Claims (1)

(57) [Claim 1] A method for photographing a distribution state of a fuel contained in an air-fuel mixture disposed in a measurement area, comprising: a plurality of base fuels having weak fluorescence characteristics; A fuel having predetermined distillation characteristics is prepared by mixing at least two kinds of fluorescent agents having different boiling points and fluorescent wavelength ranges from each other, and then the fuel and air are mixed to form a mixture, By irradiating the air-fuel mixture arranged in the measurement area with a laser for excitation of fluorescence and simultaneously photographing the fluorescence generated from each fluorescent agent separately according to each fluorescence wavelength range, the type of each fluorescent agent can be obtained. A method for photographing an air-fuel mixture, characterized by obtaining a photographed image.